Receiving and coupling part for opto-electronic transmission and/or reception element

ABSTRACT

The invention relates to a receiving and coupling part for an optoelectronic transmission and/or reception element having an opening for inserting a carrier on which the transmission and/or reception element is disposed, having a casting material that surrounds the transmission and/or reception element, and having a coupling region for the coupling of an optical fiber. The receiving and coupling part includes a cylindrical recess, one end of which contains the transmission and/or reception element, and the other end of which serves for the receiving and coupling of an optical fiber. The receiving and coupling part makes possible the arranging of the transmission and/or reception element in a transparent casting compound and the coupling of an optical fiber in a simple manner and exhibits a high degree of stability with respect to temperature fluctuations.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of copending InternationalApplication No. PCT/DE02/00903, filed Mar. 8, 2002, which designated theUnited States and was not published in English.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0002] The invention relates to a receiving and coupling part for anopto-electronic transmission and/or reception element. The receiving andcoupling part with a corresponding transmission and/or reception elementis preferably part of an inexpensive opto-electronic module that iscoupled with a POF (plastic optical fiber).

[0003] Published German Patent Application DE 199 09 242 A1 describes anopto-electronic module having a carrier with an optoelectronic converterpositioned in a modular housing. The carrier is surrounded by atransparent moldable material that protects the optical and electricalcomponents from environmental influences. A relatively long processingtime is required for curing because of a relatively large castingvolume. Another disadvantage is that differences in the coefficients ofexpansion of the carrier, components, and casting compound result in alimited stability with respect to temperature fluctuations, and stressesarise. The larger the housing and the packaged parts are, the greaterthe resulting stresses are.

[0004] In the known housing, an angle of 90° exists between the castingopening of the housing and the optical axis of a coupling region foraccepting an optical fiber. This can cause problems in the production oflenses in the molding body, since an air bubble will form given anincomplete filling of the lens mold, which sharply reduces theeffectiveness of the lens.

SUMMARY OF THE INVENTION

[0005] It is accordingly an object of the invention to provide areceiving and coupling part for a transmission and/or reception element,which overcomes the above-mentioned disadvantages of the prior artapparatus of this general type.

[0006] In particular, it is an object of the invention to provide areceiving and coupling part enabling a transmission and/or receptionelement to be configured in a transparent casting compound and enablingan optical fiber to be easily coupled. It is another object of theinvention to provide a receiving and coupling part that has a largemeasure of stability against temperature fluctuations. At the same time,the formation of air bubbles at a lens that is integrated into thecasting compound must be prevented to the greatest possible extent.

[0007] With the foregoing and other objects in view there is provided,in accordance with the invention, a receiving and coupling unit formedwith a cylindrical recess, one end of which contains the transmissionand/or reception element, and the other end of which serves forreceiving and coupling an optical fiber. The receiving and coupling partthus substantially includes a cylinder having an end at which themolding body is formed. The receiving and coupling part is thus providedwith a simple symmetrical and inexpensive structure.

[0008] The filling of the receiving and coupling part with the castingmaterial can proceed in the direction of the optical axis of thecylindrical recess, i.e. in the direction of the cylinder axis. Theother end of the cylinder is sealed on the bottom with a stamp having anegative lens shape. The positive lens shape forms therein by means ofmolding. Because the casting body is formed directly in the cylindricalrecess at which the optical fiber will be coupled, the casting materialcan be kept as small as possible, and consequently stresses based ondifferent coefficients of expansion are reduced. In addition, the curingtime is shortened accordingly. Because the casting direction coincideswith the optical axis and is not at a 90° angle to the axis as in theprior art, the lens is always completely filled with casting materialduring the filling process, which eliminates the risk of air bubblesremaining in the lens region.

[0009] Alternatively, it can also be provided that a carrier and, duringthe filling process, the casting compound as well, are inserted by wayof an opening in the wall of the cylindrical recess at an angle of 90°to the optical axis. In this variant of the invention, one end of thecylindrical recess is preferably provided with a sealing cap. The wallof the receiving and coupling part preferably consists of a conductiveplastic material and/or is sheathed in a conductive electrical layer.The electromagnetic radiation in the optical transmission element isthus absorbed and can exit the open part (i.e. the coupling region) ofthe receiving and coupling part only in a highly dampened form. Thecylindrical recess thus acts something like a hollow conductor that isbeing driven far above the cut-off wavelength.

[0010] The carrier is preferably a leadframe. The receiving and couplingpart can preferably be connected to ground lines by way of theleadframe. The lines are inserted into the receiving and coupling partin such a way that an optical transmission and reception element can bealigned in all three dimensions relative to the optical axis and theexterior dimensions of the receiving and coupling part. Moldings aretherefore provided, which set the optical elements and the optical axisin relation to the outer diameter of the receiving and coupling part ina simple joining step. The positioning of the optical element on theleadframe thus occurs with a high position precision relative to theoptical axis.

[0011] The inner diameter of the cylindrical recess matches the outerdiameter of an optical fiber that is to be coupled. By the insertion ofthe optical fiber—which is a plastic fiber, an HPCS/HCS fiber, or amultimode glass fiber with a core diameter of 50 μm—into the receivingand coupling part, the optical fiber is securely held on the opticalaxis.

[0012] In a preferred development of the invention, the leadframeextends parallel to the optical axis of the cylindrical recess of thereceiving and coupling part. To a certain extent, it is thus led awayfrom the back of the receiving and coupling part. The advantage of thisis the small dimension of the receiving and coupling part perpendicularto the optical axis. The disadvantage is that, with the leadframealigned parallel to the optical axis of the cylindrical recess, theoptical transmission and/or reception element must be mounted on aportion of the leadframe that is bent 90°.

[0013] In an alternative development, the leadframe is installedvertical to the optical axis of the cylindrical recess. That way, theoptical converters can be built on a planar leadframe.

[0014] According to a preferred development of this variant, theleadframe, outside the receiving surface for the optical transmissionand/or reception element, is bent in the shape of an S prior to afilling of the receiving and coupling part, namely the cylinder, in thedirection of the optical axis. This guarantees that the receivingsurface for the optical transmission and/or reception element protrudesinto the interior of the cylindrical recess.

[0015] The receiving and coupling part, which, as described above,either consists of an electrically conductive material or possesses agalvanically applied metal sheathing, is either non-conductive or isinsulated from the leadframe at the location where the leadframe is ledout of the receiving and coupling part vertically to the longitudinalaxis.

[0016] For the purpose of positioning the leadframe, passive aligningstructures are preferably provided at the receiving and coupling partand the leadframe, which interlock.

[0017] In a preferred development, the optical transmission and/orreception elements are installed on a completely planar leadframe, notan S-shaped leadframe. The planar leadframe is led into the cylindricalrecess through a side opening in the wall of the receiving and couplingpart. It is positioned exactly on the optical axis of the cylindricalrecess.

[0018] The receiving and coupling part is cylindrical in the region ofthe fiber guidance, so that the optical fiber is led in the innercylinder. The receiving and coupling part can be fixed in a plug housingby the outer cylinder. The receiving and coupling part includes passivealigning marks for the assembling of the receiving and coupling part ata plug housing and/or circuit board.

[0019] It can be further provided that ridges for mechanical locking areinstalled on the outer cylinder, i.e. on the exterior of the wall of thecylindrical recess. That way, the receiving and coupling part can beprevented from sliding out during its assembly at a plug housing. Suchlocking devices, which are U-shaped, for example, can be constructeddifferently for a receiving and coupling part with a transmissionelement or with a reception element. A locking mechanism could also beprovided in an annular form on the exterior wall by a small wedge-shapedelevation.

[0020] It is not always necessary to use two separate receiving andcoupling parts for realizing the transmission and reception componentsof a transceiver. It can also be provided that the receiving andcoupling part is constructed as a double chamber including thetransmission and reception elements in separate parallel regions. Thespacing of the two cylinder axes corresponds to the spacing of the twoaxes of the optical fiber of a mechanical plug system. Locking with aclock type rotation is then no longer possible. Locking occurs by usinga wedge shaped ring structure on the two outer cylinders, for example.

[0021] A passive alignment is provided in this exemplary embodiment bythe dimensions of the two outer cylinders, which fit positively into thecorresponding recesses at an appertaining plug housing. In order tosuppress an electrical crosstalk from the transmission converter ontothe reception converter, the connecting wall between the two chambers iselectrically conductive. This can be realized by using an electricallyconductive casting compound, for example.

[0022] Another embodiment provides openings in the connecting wall forpreventing electrical crosstalk. These openings are constructed suchthat they are coated or filled with an electrically conductive layer,and they represent a metallically conductive wall for theelectromagnetic radiation.

[0023] Other features which are considered as characteristic for theinvention are set forth in the appended claims.

[0024] Although the invention is illustrated and described herein asembodied in a receiving and coupling part for opto-electronictransmission and/or reception element, it is nevertheless not intendedto be limited to the details shown, since various modifications andstructural changes may be made therein without departing from the spiritof the invention and within the scope and range of equivalents of theclaims.

[0025] The construction and method of operation of the invention,however, together with additional objects and advantages thereof will bebest understood from the following description of specific embodimentswhen read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a sectional view showing the basic structure of areceiving and coupling part;

[0027]FIG. 2 is a sectional side view and a plan view of the receivingand coupling part constructed as shown in FIG. 1, but with ground pinsthereon;

[0028]FIG. 3 is a sectional view taken through another exemplaryembodiment of a receiving and coupling part together with a plug housingthat can be placed on the receiving and coupling part;

[0029]FIG. 4 is a sectional view taken through a receiving and couplingpart during the arranging of a photodetector;

[0030]FIG. 5 is a sectional view taken through a receiving and couplingpart while configuring a transmission element and subsequent toseparating the leadframe;

[0031]FIG. 6 are front and sectional views of a fully assembledreceiving embodiment of a receiving and coupling part;

[0032]FIG. 7 are front and sectional views of a fully assembledtransmission embodiment of a receiving and coupling part;

[0033]FIG. 8 is a schematic view showing the coupling of a receiving andcoupling part in a plug housing;

[0034]FIG. 9 are side, rear, and front views of another exemplaryembodiment of a receiving and coupling part;

[0035]FIG. 10 shows a step of attaching a receiving element on aleadframe in a method for producing the receiving and coupling partshown in FIG. 9;

[0036]FIG. 11 shows a step in fabricating the receiving and couplingpart shown in FIG. 9;

[0037]FIG. 12 shows an exemplary embodiment of a receiving and couplingpart with a receiving element that has been slightly modified comparedto the exemplary embodiment represented in FIG. 9;

[0038]FIG. 13 is a front view of a receiving and coupling part having acarrier with both a transmission diode and a monitor diode;

[0039]FIG. 14 shows an alternative development of a receiving andcoupling part with a planar carrier;

[0040]FIG. 15 are side and sectional views of the receiving/couplingpart represented in FIG. 14 during the fabrication thereof; and

[0041]FIG. 16 shows a step in the fabrication of several receiving andcoupling parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Referring now to the figures of the drawing in detail and first,particularly, to FIG. 1 thereof, there is shown the basic components ofa receiving and coupling part. These components consist of a cylinder 1,which includes a wall 101 that defines a cylindrical recess 102 andsurrounds the recess 102. The cylinder 1 is symmetrically constructedand includes an optical axis 103. The axis 103 forms the optical axis ofa transmission or reception element that is disposed in the receivingand coupling part in a casting material. The cylinder 1 consists of aconductive injection molding material or is surrounded by anelectrically conductive sheathe.

[0043] For receiving a leadframe that forms a carrier and that includesthe respective optical converter element (for instance a photodiode orRCLED), the receiving and coupling part is provided with receivingsockets 104, and the cylinder wall is reinforced in this region 105.Ground pins of the leadframe are inserted into the receiving sockets104. These ground pins guarantee the ground connection of the receivingand coupling part with the printed circuit board for ground shieldingpurposes.

[0044] The receiving and coupling part is also referred to as a CAI(cavity-AS interface) housing that serves for receiving a transmissionand/or reception element disposed on a carrier in a casting material andalso for coupling an optical fiber. The receiving and coupling part isreferred to as the CAI housing hereinafter.

[0045]FIG. 2 shows slight variants in which the ground pins 104′ areco-injected directly when fabricating the CAI housing. The aligning of aleadframe then occurs by way of guide slots 106 at the margin region ofthe cylinder 1.

[0046] All geometric dimensions are defined by the CAI housing withreference to optically coupling an optical fiber. Thus, the dimensionsof the outer diameter, inner diameter, and open path distance to thecasting body in the CAI housing represent a standardized mechanicalinterface to a plug that is to be attached. The dimension of a plughousing must match the dimensions of the CAI housing so that the CAIhousing can be fit into a plug housing.

[0047]FIG. 3 shows the essential dimensions A, B, C, D that must betransferred from the CAI housing into a plug housing 2.

[0048] In the exemplary embodiment shown in FIG. 3, the cylinder 1 alsohas a reinforced region 105. A positive region, for instance asurrounding trench 107 is provided, which allows the locking of thecylinder 1 of the CAI housing in the wall of the plug housing 2.Completely surrounding the CAI housing by the plug housing 2 istherefore unnecessary. Rather, the cylinder 1 of the CAI housing canprotrude into the plug housing 2 freely like a beak.

[0049]FIG. 4 shows a section through a structure for fabricating aphotodetector. The CAI housing with the cylinder 1 is sealed on thebottom by a stamp 3. A coupling lens 302 is constructed on the stampsurface 301 in negative form and with a fiber stop locking mechanism.The fiber stop locking mechanism, a fiber stop ring to be exact, isconstructed in the outer region and includes a nose 303 with a length of50 μm relative to the lens vertex. A leadframe 4 with a photodiode 5 hasbeen immersed in the casting body and is cured. The cylinder interior isfilled with a casting compound in the direction of the optical axis,i.e. from above.

[0050] The leadframe forms a cathode contact K and an anode contact A,which extend in the direction of the optical axis. The photodiode 5 iscontacted using bond wires 6 a, 6 b, respectively.

[0051]FIG. 5 shows a configuration corresponding to the configuration ofFIG. 4, but with a transmission element 6. It is noted that theleadframe with the contact elements K, A forms a 90° angled region 401on which the transmission element 6, or the reception element 5 in FIG.4, is mounted.

[0052]FIG. 6 shows front and sectional views of the CAI housingconstructed in a receiver embodiment and mounted on an Al-laminated flexfilm circuit carrier. The “optics” are limited to the region of thetransparent casting body. The electrical wiring is realized as known inthe prior art. The Al film serves for shielding against electromagneticradiation as well as for heat removal.

[0053]FIG. 7 shows a CAI housing constructed in a transmissionembodiment and mounted on an Al-laminated flex film circuit carrier.

[0054]FIG. 8 shows the CAI housing constructed in a receiver embodimentwith an SMI (small multimedia interface) plug housing 2. An attached POF(plastic optical fiber) plug 7 with an optical fiber 8 is inserted intothe CAI housing and fixed in place exclusively by the dimension of theCAI housing. A mechanical interface exists. With this design, any formof plug can be provided with an optical transceiver consisting of atransmitting and receiving module, while at the same time thestandardized mechanical dimension of the CAI housing is preserved.

[0055]FIG. 9 shows an exemplary embodiment wherein the leadframe 4 isled from the cylinder 1 vertically relative to the optical axis. Theleadframe is therein bent into an S shape, so that it protrudes in theinterior of the cylindrical recess 102 and is completely covered duringthe filling with a casting material.

[0056]FIG. 10 shows the leadframe 4 with a receiver diode 5. It can berecognized in the sectional view that the leadframe is curved in theshape of an S.

[0057]FIG. 11 shows the receiving and coupling part after placing theleadframe into the CAI housing. The CAI housing formed by the cylinder 1has two open ends. The lower end is sealed by a stamp 3. The castingmaterial is filled in using the upper end. After curing the castingmaterial, the stamp is removed.

[0058]FIG. 12 shows a slight alternative development of the CAI housingof FIG. 11 wherein additional passive aligning elements 18 are provided.

[0059]FIG. 13 shows an exemplary embodiment in which a monitor diode 9is attached to the leadframe in addition to a transmission diode 6.

[0060] In the exemplary embodiment shown in FIG. 14, the leadframe isdisposed perpendicular to the optical axis. But the leadframe isconstructed planar. Accordingly, it is inserted into the cylindricalrecess 102 by way of a side opening 10 in the wall of the cylinder 1. Afilling with casting material also occurs by way of opening 10.

[0061]FIG. 15 shows the receiving and coupling part subsequent to theintroduction of a stamp 3 on one end of the cylinder 1. In order toprovide a cavity for filling, the other end of the cylinder is sealedwith a cap 11.

[0062] Lastly, FIG. 16 shows a step in a method in which a commonleadframe is used for several CAI housings. Subsequent to bending theleadframe legs using a press element 12, the legs are separated along acut line 13.

[0063] It should be noted that the invention is not limited to thedescribed exemplary embodiments, but encompasses modifications andvariations that fall within the scope of protection defined by theclaims.

We claim:
 1. A receiving and coupling part, comprising: a carrier withan opto-electronic transmission and/or reception element; an opening forinserting said carrier; a casting material surrounding said transmissionand/or reception element; a coupling region for coupling an opticalfiber; and a cylindrical recess having a first end and a second end;said first end of said cylindrical recess containing said transmissionand/or reception element; and said second end of said recess forreceiving and coupling an optical fiber.
 2. The receiving and couplingpart according to claim 1, wherein: said cylindrical recess has a firstopen end forming said opening for inserting said carrier; and saidcylindrical recess has a second open end forming for receiving andcoupling of said optical fiber.
 3. The receiving and coupling partaccording to claim 1, further comprising: a wall defining saidcylindrical recess; said cylindrical recess extending along alongitudinal axis; said opening for inserting said carrier being formedin said wall of said cylindrical recess and extending substantiallyperpendicular to said longitudinal axis of said cylindrical recess. 4.The receiving and coupling part according to claim 1, further comprisingan electrically conductive plastic material.
 5. The receiving andcoupling part according to claim 1, further comprising a coating of anelectrically conductive layer.
 6. The receiving and coupling partaccording to claim 1, wherein said cylindrical recess has an innerdiameter corresponding to an outer diameter of said optical fiber to becoupled.
 7. The receiving and coupling part according to claim 1,wherein said carrier is a leadframe enabling said transmission and/orreception element to be electrically contacted.
 8. The receiving andcoupling part according to claim 7, wherein: said cylindrical recess hasan optical axis; and said leadframe longitudinally extends parallel tosaid optical axis of said cylindrical recess.
 9. The receiving andcoupling part according to claim 7, wherein: said cylindrical recess hasan optical axis; and said leadframe extends vertically to said opticalaxis of said cylindrical recess.
 10. The receiving and coupling partaccording to claim 7, wherein: said leadframe is curved in an S shapehaving a region protruding into said cylindrical recess.
 11. Thereceiving and coupling part according to claim 10, wherein: said carrieris disposed at said first end of said cylindrical recess; and said firstend of said cylindrical recess enables said casting material to beintroduced.
 12. The receiving and coupling part according to claim 7,wherein said leadframe is planar.
 13. The receiving and coupling partaccording to claim 12, further comprising: a cover element; and a walldefining said cylindrical recess; said first end of said cylindricalrecess accommodating said planar leadframe and being sealed by saidcover element; and said opening for inserting said carrier being formedin said wall of said cylindrical recess.
 14. The receiving and couplingpart according to claim 12, further comprising: a fiber stop ring formedin said casting material; said fiber stop ring surrounding saidintegrated lens; and said fiber stop ring for preventing a face of saidoptical fiber from hitting said coupling lens.
 15. The receiving andcoupling part according to claim 1, wherein said casting material formsan integrated lens.
 16. The receiving and coupling part according toclaim 1, further comprising: a double chamber having parallel regions; acoupling element; and a plurality of coupling regions; saidopto-electronic transmission and/or reception element being atransmission element; said coupling element and said transmissionelement configured in separate ones of said parallel regions; and saidplurality of coupling regions for coupling said coupling element andsaid transmission element with said optical fiber.
 17. The receiving andcoupling part according to claim 1, wherein: said transmission and/orreception element is configured on said carrier; and said carrier doesnot have electrical driver circuits or reception circuits configuredthereon.
 18. The receiving and coupling part according to claim 17,further comprising a monitor diode configured on said carrier; saidcarrier having only said monitor diode and said transmission and/orreception element configured thereon.
 19. The receiving and couplingpart according to claim 17, in combination with a plug housing, wherein:the receiving and coupling part includes an exterior wall withstructures for fixing the receiving and coupling part to the plughousing.